This invention relates to a storage system and, in particular, relates to control of a storage system.
PCT International Publication No. WO 2010/131373 discloses a technique that each processor in charge of I/O of a volume caches control information on data caching in a shared memory to a local memory (control caching) to improve performance of a storage system.
When updating control information in a local memory, a processor synchronously updates the control information in the shared memory. This operation allows another processor that takes over the assignment of the processor at some failure to acquire the latest data caching control information from the shared memory, preventing performance degradation in the storage system because of a lowered cache hit rate.
In addition to this, data caching, which caches user data from a non-volatile storage medium to a cache memory to improve the performance of a storage system, is widely applied to storage systems.